Radio communication apparatus

ABSTRACT

A radio receiving apparatus for receiving the variable-length RLC PDU data in an RLC layer includes the buffer memory sectioned into a plurality of areas having a predetermined maximum data length of the RLC PDU data. By referring to a sequence number SN included in each received RLC PDU data, the radio receiving apparatus stores the RLC PDU data having an identical sequence number SN into an identical area, and assembles an RLC SDU data on a basis of the RLC PDU data stored in each area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2006-224107, filed on Aug. 21,2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radio communication apparatus fortransmitting and/or receiving a variable-length RLC PDU data in an RLClayer belonging to Layer 2 forming a radio communication protocol layer,and more particularly radio receiving apparatus enabling efficientlystorage of a received RLC PDU data into a buffer memory.

2. Description of the Related Art

A W-CDMA system becomes widely used today, as a third generation (3G)radio communication system. Further, a standard called HSDPA (High-SpeedDownlink Packet Access) comes into practical use to obtain high-speed(14 Mbps maximum) data communication in W-CDMA. HSDPA is also called as3.5G system because of an improved version of the 3G system. Thestandardization is carried out by 3GPP (the 3rd Generation PartnershipProject), an association for standardizing the 3G system.

HSDPA has the features of (1) shared use of one physical channel by aplurality of mobile terminals (UE) in time division, (2) automaticselection of higher speed modulation system and coding system dependingon an electric wave condition, (3) adopting hybrid ARQ incorporatingretransmission control (ARQ) combined with correction coding processing,and so on.

FIG. 1 shows a diagram illustrating a data structure of Layer 2 in theprotocol architecture corresponding to HSDPA. Layer 2 is divided intosublayers of MAC (Medium Access Control)-hs, MAC-d, and RLC (Radio LinkControl).

FIG. 2 shows a diagram illustrating the format of RLC PDU (Protocol DataUnit). RLC PDU shown in FIG. 2 is an Acknowledge Mode RLC PDU enablingdata delivery confirmation control and data retransmission control. RLCPDU includes D/C bit for distinguishing between a user data and acontrol data; a sequence number (SN) indicating the sequential order ofRLC-PDU; polling bit P indicating the presence/non-presence of adelivery confirmation request; area HE indicating information of theuser data extension area; length indicator LI; E bit; data storage areaData; and padding bit PAD or piggyback (Piggybacked STATUS PDU).

The data size of RLC PDU is fixed to, for example, 42 octets, 82 octetsor 122 octets (where 1 octet is 8 bits), which is not changed duringcommunication. RLC PDU is identified by the sequence number SN, whichhas a numeric value ranging from, for example, 0 to 4,095 maximum.

In RLC shown in FIG. 1, on the transmission side of RLC, a transmissiondata RLC SDU (Service Data Unit) fed from an upper layer is divided intoa plurality of RLC PDUs, and forwarded to the lower MAC-d layer, after asequence number SN is given to identify each RLC PDU.

Also, on the reception side of RLC, when the RLC PDUs are received fromthe lower MAC-d layer, by being sorted in order of the sequence numberSN, the RLC PDUs are merged to assemble RLC SDU, and then transferred tothe upper layer. At this time, when there is a missing sequence numberSN, a retransmission request of RLC PDU corresponding to the missing SNis initiated.

Therefore, the transmission side of RLC is required to retain thetransmitted RLC PDU in a buffer (memory) until the notification ofdelivery confirmation is received from the reception side of RLC. Also,the reception side of RLC is required to keep a buffer for the RLC PDUof which SN is missing, when performing RLC SDU assembly.

FIG. 3 shows a diagram illustrating the operation on the reception sideof RLC in the HSDPA system specified by 3GPP. In the present andsubsequent figures, “H” denotes an RLC Header, and “Data” denotes aPayload.

When a missing sequence number is detected on the reception side of RLC,the transmission side is notified of the missing sequence number SN ofthe RLC PDU concerned, in the form of a retransmission request. As shownin FIG. 3( a), for example, SN=2 is missing, and the retransmissionrequest therefor is initiated. At this time, on the reception side ofRLC, a buffer area for originally storing RLC PDU of SN=2 is kept idle.The buffer size to be kept idle can easily be obtained because of thefixed length of RLC PDU. When the reception side of RLC receives RLC PDUof SN=2 as a retransmission data [refer to FIG. 3( b)], the received PDUis allocated in the buffer area having been kept idle for the PDUconcerned, and the assembly of RLC SDU is performed [refer to FIG. 3(c)].

In Japanese laid-open Patent Publication No. 2006-20044, there isdisclosed a memory management method in the MAC-hs sublayer, enablingreduction of the increase of the memory amount without need of acomplicated memory control method, by dividing a variable-length MAC-hsPDU into each unit of RLC PDU and storing into a shared memory (buffer)together with a sequence number.

After the realization of the above-mentioned 3.5G mobile communicationsystems by HSDPA, subsequently, migration to the fourth generation (4G)systems will be expected in early stages so as to realize higher speedand larger capacity. However, in the present estimation, one more stagecalled as “3.9G” (which may also be called as “Super 3G”) will beintroduced before migration to 4G systems. As the communication speed ofthe 3.9G systems, a maximum speed of 100 Mbps, or of that order, isassumed.

In 3GPP at present, as the 3.9G specification, a study is in progress tomodify RLC PDU from fixed length, as shown in FIGS. 1, 2, to variablelength.

FIG. 4 shows a diagram illustrating an assumed configuration of the RLCsublayer when the RLC PDU is modified to have variable length. As shownin FIG. 4, when the RLC PDU is modified to have variable length, thesequence number SN is used as a number to identify RLC SDU. To identifyRLC PDU constituting each RLC SDU, assumedly, an SI (Segment Indicator)is introduced. In case of the fixed-length RLC PDU, the number of RLCPDUs constituting a fixed-length RLC SDU is uniquely determined.Accordingly, the RLC SDU can be identified when the RLC PDU isidentified. However, when the RLC PDU is modified to have variablelength, the number of RLC PDUs constituting each RLC SDU is not uniquelydetermined. Therefore, it becomes necessary to introduce any symbol soas to identify RLC SDU further. Thus, the sequence number SNconventionally used to identify each RLC PDU is used as a symbol toidentify RLC SDU, and the aforementioned segment indicator SI is newlyintroduced as the symbol to identify RLC PDU.

FIG. 5 shows an exemplary format when RLC PDU is modified to havevariable length. As described above, when RLC PDU is modified to havevariable length, the sequence number SN becomes the number to identifyRLC SDU, and RLC PDU is to be identified by the combination of the abovesequence number SN and the segment indicator SI belonging thereto.

In the format, the reason for providing a plurality of areas for thesegment indicator SI is that, when the RLC PDU being divided into avariable length is further divided, additional attachment of the segmentindicator SI becomes necessary to identify further divided RLC PDU. Atthe retransmission control when RLC PDU is modified to have variablelength, the following problem will be produced.

FIG. 6 shows a diagram explaining the operation on the reception side ofRLC when the RLC PDU is modified to have variable length. When a missingRLC PDU is detected on the reception side of RLC, the transmission sideis notified of both the sequence number SN and the segment indicator SIcorresponding to the above missing RLC PDU, as a retransmission request.As shown in FIG. 6( a), for example, in case of a missing RLC PDU ofSN=0, SI=1, the retransmission thereof is requested. At this time,because the data length of the missing RLC PDU is unknown, it is notpossible to keep an idle buffer area for the missing RLC PDU so as tostore RLC PDUs in order of the segment indicator SI [refer to FIG. 6(b)].

Assuming to keep the idle buffer area beforehand, it is necessary toassume to receive RLC PDU having a preset maximum length, which resultsin a high possibility of wasteful buffer area consumption.

In Patent document 1, a variable-length MAC-hs PDU is divided into eachfixed-length RLC PDU, which does not produce any problem because the RLCPDU is divided later in the RLC sublayer. However, it is not possible toapply the same method in an upper layer than the RLC sublayer because ofno data division performed. Also, in the high-speed communication suchas Super 3G, efficient communication can be achieved by elongating eachdata length, and therefore, it is not preferable to introduce excessivedivision of data.

FIG. 7 shows a diagram explaining a use state of the buffer areaconsidering the maximum length of the RLC PDU. For example, assuming themaximum length of the RLC PDU is 1,500 bytes, it is necessary to preparea buffer area of 1, 500 bytes for one RLC PDU. Thus, the buffer areasshown by the broken lines in the figure are wasted.

Also, when storing RLC PDUs in a packed manner in order of reception,RLC PDUs having an identical sequence number SN may not always bereceived consecutively. When RLC PDUs of different sequence numbers SNare received mixed, it is necessary to assemble RLC SDU after extractingRLC PDUs having an identical sequence number SN. Thus, the assembly toRLC SDU becomes complicated.

Accordingly, it is an object of the present invention to provide radioreceiving apparatus in case of the variable-length RLC PDU, enablingefficient storage of received RLC PDUs into the buffer without wastingthe buffer area.

SUMMARY OF THE INVENTION

As a first configuration of the radio receiving apparatus according tothe present invention to achieve the aforementioned object, in the radioreceiving apparatus which receives a variable-length RLC PDU data in anRLC layer belonging to Layer 2 forming a radio communication protocollayer, and assembles one RLC SDU data from one or a plurality of RLC PDUdata, there are provided a buffer memory having a predetermined maximumdata length of the RLC SDU data and being sectioned into a plurality ofareas; and a controller referring to first sequence information includedin the header of the received RLC PDU data, storing the RLC PDU datahaving the identical first sequence information into an identical buffermemory area, and assembling the RLC SDU data on a basis of the RLC PDUdata stored in each area.

As a second configuration of the radio receiving apparatus according tothe present invention, in the above first configuration, when storingthe plurality of RLC PDU data into one buffer memory area, thecontroller stores the plurality of RLC PDU data into the above area inorder of reception, and to assemble the RLC SDU data, the controllersuccessively reads out the plurality of RLC PDU data in order of thesequence identified by second sequence information being included ineach header of the plurality of RLC PDU data stored in the above area,sorts in order of the above sequence, and assembles the RLC SDU data.

As a third configuration of the radio receiving apparatus according tothe present invention, in the above second configuration, there areprovided a management memory storing the second sequence information,the top address and the data length of each RLC PDU data stored in eachbuffer memory area as a set of data, and the controller successivelyrecords the set of data including the second sequence information, thetop address and the data length of each RLC PDU data, in order ofreception of the plurality of RLC PDU data.

As a fourth configuration of the radio receiving apparatus according tothe present invention, in the above third configuration, when thereception sequence of the plurality of RLC PDU data is continuous in theregular order of the second sequence information, with regard to theplurality of RLC PDU data having the consecutive second sequenceinformation, the controller records into the management memory thesecond sequence information of the first RLC PDU data, the secondsequence information of the last RLC PDU data, the top address of thefirst RLC PDU data, and the data length of the entire plurality of RLCPDU data having the consecutive second sequence information, as a set ofdata.

As a fifth configuration of the radio receiving apparatus according tothe present invention, in the above second configuration, when storingthe plurality of RLC PDU data into one buffer memory area, thecontroller stores into the buffer memory of which address is identifiedby the first sequence information and top address information includedin each header of the above plurality of RLC PDU data, and reads out theplurality of RLC PDU data in order of storage of the plurality of RLCPDU data stored in the above area, and assembles the RLC SDU data, andfurther, the top address information is given according to thetransmission sequence and the data length of the plurality of RLC PDUdata.

As a sixth configuration of the radio receiving apparatus according tothe present invention, in the above fifth configuration, on receivingthrough retransmission control an RLC PDU data having top addressinformation identical to the buffer memory address in which the RLC PDUdata is already stored, the controller overwrites the received RLC PDUdata on the buffer memory address identified by the above top addressinformation.

As a seventh configuration of the radio receiving apparatus according tothe present invention, in the above first configuration, the firstsequence information is a sequence number identifying an RLC SDU data.

According to the present invention, when the RLC PDU data in the RLClayer is modified to have variable length, a buffer memory for storingthe RLC PDU data received in radio receiving apparatus can be usedefficiently without being wasted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram illustrating a data structure of Layer 2 in theprotocol architecture corresponding to HSDPA.

FIG. 2 shows a diagram illustrating an RLC PDU format.

FIG. 3 shows a diagram illustrating the operation on the reception sideof RLC in the HSDPA system specified by 3GPP.

FIG. 4 shows a diagram illustrating an assumed configuration of the RLCsublayer when the RLC PDU is modified to have variable length.

FIG. 5 shows an exemplary format when the RLC PDU is modified to havevariable length.

FIG. 6 shows a diagram explaining the operation on the reception side ofRLC when the RLC PDU is modified to have variable length.

FIG. 7 shows a diagram explaining a use state of a buffer areaconsidering the maximum length of the RLC PDU.

FIG. 8 shows a configuration diagram of radio receiving apparatusaccording to an embodiment of the present invention.

FIG. 9 shows a diagram illustrating an exemplary configuration of an RLCbuffer according to an embodiment of the present invention.

FIG. 10 shows a diagram illustrating another management form using amanagement memory for managing the RLC PDUs being stored in an RLCbuffer 11 on a basis of the sequence number SN.

FIG. 11 shows a diagram illustrating another exemplary RLC PDU formatand an exemplary RLC buffer configuration according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention are describedhereinafter referring to the charts and drawings. However, theembodiments described below are not intended to limit the technicalscope of the present invention. FIG. 8 shows a configuration diagram ofradio receiving apparatus according to an embodiment of the presentinvention. The radio receiving apparatus is a radio communicationterminal unit 10 or a radio base station unit 20. Radio communicationterminal unit 10 and radio base station unit 20 respectively includesRLC buffers 11, 21, and RLC controllers 12, 22 for performing readoutcontrol and write control thereto. The embodiment described in thefollowing is a buffer configuration and buffer control on the receptionside of RLC. In case of application to a downlink such as HSDPA, radiocommunication terminal unit 10 is the radio receiving apparatus of thepresent invention. Meanwhile, in case of application to an uplink suchas HSUPA, radio base station unit 20 is the radio receiving apparatus ofthe present invention. Hereafter, the description is made using RLCbuffer 11 and RLC controller 12 of radio communication terminal unit 10as an example. However, the embodiment of the present invention is alsoapplicable to RLC buffer 21 and RLC controller 22 of radio base stationunit 20. RLC controllers 12, 22 may be configured of either hardware orsoftware, or the combination thereof.

FIG. 9 shows a diagram illustrating an exemplary configuration of theRLC buffer according to the embodiment of the present invention. RLCbuffer 11 is sectioned on a basis of the sequence number SN identifyingan RLC SDU. For each SN, a buffer amount having a predetermined maximumRLC SDU length (for example, 1,500 bytes) is given.

RLC PDUs are transmitted in the format shown in the above FIG. 5, havinga header including a sequence number SN and a segment indicator SI. Whenreceiving the RLC PDUs, RLC controller 12 refers to the sequence numberSN included in the header of each RLC PDU, distributes the RLC PDUs on abasis of SN, and stores the received RLC PDUs into each buffer areaassigned to each SN.

Because the maximum length of each RLC PDU is predetermined, bydistributing the RLC PDUs on a basis of each sequence number identifyingeach RLC SDU, the RLC PDUs can be efficiently stored into RLC buffer 11without considering the data lengths of the variable-length RLC PDUs.Typically, by distributing the RLC PDUs on a basis of each SN, aplurality of RLC PDUs can be stored on a basis of each sequence number.As long as the sequence number SN is identical, the data length of theentire RLC PDUs having the identical sequence number SN can be storedwithout exceeding the maximum RLC SDU length. Thus, it is possible tostore the variable-length RLC PDUs into RLC buffer 11 as efficiently aspossible.

In FIG. 9( a), it is assumed that the RLC PDUs are received in order of(1) SN=0, SI=0, (2) SN=1, SI=0, (3) SN=0, SI=2, and (4) SN=0, SI=1,similar to FIG. 6. Then, the RLC PDUs of (1) SN=0, SI=0, (3) SN=0, SI=2,and (4) SN=0, SI=1 are stored into an area assigned to SN=0 in RLCbuffer 11 in order of reception, while the RLC PDU of (2) SN=1, SI=0 isstored into an area assigned to SN=1 in RLC buffer 11. The RLC PDUs of(3) SN=0, SI=2, and (4) SN=0, SI=1 are stored in order of reception,though the reception sequence is reversed due to retransmission.

FIG. 9( b) is information stored in the management memory for managingRLC buffer 11. The management memory is, for example, an internal memoryof RLC controller 12. Or, a portion of the area of RLC buffer 11 may beused as management memory. Or otherwise, it may also be possible toprovide a dedicated memory for the management memory.

In the management memory also, the RLC PDUs stored in RLC buffer 11 aremanaged on a basis of each sequence number SN. In the management memory,there are stored a top address, a data length, and bit information (LSI:Last Segment Indicator) indicative of the last segment indicator SI inthe sequence number SN concerned, for each segment indicator SI of RLCPDU.

For each sequence number SN, when the entire RLC PDUs up to the RLC PDUof LSI=1, having the last segment indicator SI, are completely stored inRLC buffer 11, RLC controller 12 refers to the management memory shownin FIG. 9( b), and reads out from the top address of each RLC PDU inorder of the segment indicator SI. Thus, RLC controller 12 sorts RLCPDUs in order of the segment indicator SI, and assembles an RLC SDU.

In FIG. 9( a), with regard to the RLC PDUs having a sequence numberSN=0, RLC controller 12 reads out in order of the segment indicator SI,namely, in order of (1) SN=0, SI=0, (4) SN=0, SI=1 and (3) SN=0, SI=2,so as to assemble the RLC SDU.

FIG. 10 shows a diagram illustrating another management form using amanagement memory for managing the RLC PDUs being stored in an RLCbuffer 11 on a basis of each sequence number SN. The management memoryshown in FIG. 10 includes an area capable of storing a range havingconsecutive segment indicators SI. An area “a” stores the first SI andthe last SI of the consecutive segment indicators SI. As shown in FIG.10( a), as to an RLC PDU having a sequence number SN=0, when the RLC PDUhaving SI=0 is received, an identical SI=0 is stored in the area “a” asthe consecutive first SI and the last SI because only one RLC PDU hasbeen received so far. Also, the top address of the RLC PDU having SI=0is stored, together with the data length thereof.

Subsequently, when an RLC PDU having SI=1 consecutive from SI=0 isreceived, in the area “a”, there are stored SI=0 as the firstconsecutive SI, and SI=1 as the last SI. The top address remains the topaddress of the RLC PDU having SI=0, and as the data length, a total datalength of the RLC PDU having SI=0 and the RLC PDU having SI=1 is stored.

When RLC PDUs are received in order of the segment indicator SI, andstored in RLC buffer 11 in order of the segment indicator SI, theconsecutive plurality of RLC PDU can be read out by specifying the topaddress and the data length. Thus, it is possible to manage the RLC PDUsstored in RLC buffer 11 with a smaller amount of data, as compared tostoring the top address and the data length for each segment indicatorSI, by which the memory capacity of the management memory can bereduced. In case of FIG. 10( b), by storing the top address of SI=0 andthe total data length of SI=0 and SI=1, it is possible to manage two RLCPDU of SI=0 and SI=1 which are stored consecutively using one set ofdata.

In FIG. 10( c), further, an RLC PDU having SI=2 consecutive from SI=1 isreceived, and in the area “a”, there are stored SI=0 as the consecutivefirst SI, and SI=2 as the last SI. As the top address remains the topaddress of the RLC PDU having SI=0, and as data length, the total datalength of RLC PDU from SI=0 to SI=2. As such, as long as the segmentindicators SI are consecutive, it is possible to manage the plurality ofRLC PDUs consecutively stored, using one set of data, and thus, thememory capacity of the management memory can be reduced.

FIG. 11 shows a diagram illustrating another exemplary RLC PDU formatand an exemplary RLC buffer configuration according to an embodiment ofthe present invention. In the exemplary RLC PDU format shown in FIG. 11(a), a segment pointer SP is employed in place of the segment indicatorSI shown in FIG. 5. The segment pointer SP is an offset address from thetop address of each buffer area of RLC buffer 11 for each sequencenumber SN.

RLC buffer 11 is sectioned in advance on a basis of the maximum lengthof the RLC PDU (for example, 1,500 bytes), and the address range of thebuffer area corresponding to each sequence number can be identified.Accordingly, by specifying the storage positions of the plurality of RLCPDUs for each sequence number SN by use of the address, each RLC PDU canbe stored in order, even if the RLC PDU has variable length.

As shown in FIG. 11( b), for example, with regard to the sequence numberSN=0, when RLC PDUs specified by the segment pointers (1) SP=0x0000, (2)SP=0x0100 and (3) SP=0x01A0 are received, the storage is performed intothe buffer area of SN=0, using each address specified by each segmentpointer SP as top address. Even when the reception sequence is not theoriginal sequence of (1), (2), (3), but the reception is made, forexample, in order of (1), (3), (2), RLC controller 12 stores the RLC PDUof (1) SP=0x0000 into the address specified by the segment pointer SP,and also stores the next received RLC PDU of (3) SP=0x01A0 into theaddress specified by the segment pointer SP. At this time, in the bufferarea, there is an idle buffer area for the RLC PDU of (2) SP=0x0100between the RLC PDU of (1) SP=0x0000 and the RLC PDU of (3) SP=0x01A0.On receipt of the RLC PDU of (2) SP=0x0100, the storage is made in theaddress specified by the segment pointer SP (2) SP=0x0100, and thus, theRLC PDUs are stored in the buffer area in order of (1) SP=0x0000, (2)SP=0x0100 and (3) SP=0x01A0.

In the format shown in FIG. 11( a), an LSI bit defined next to thesegment pointer SP is a bit for identifying the last RLC PDU among RLCPDUs of each sequence number SN. RLC controller 12 recognizes that theRLC PDU having LSI=1 is the last RLC PDU of the sequence number SNconcerned, and confirms whether or not the entire RLC PDUs correspondingto the sequence number SN have already been received and stored in theareas preceding the storage position of the RLC PDU having LSI=1, of thebuffer area of the sequence number SN concerned. When the entire RLCPDUs are already stored, RLC controller 12 reads out in the regularorder of the storage, and assembles RLC SDU. When the entire RLC PDUsare not stored yet, RLC controller 12 performs processing to store theentire RLC PDUs by standing by further, or initiating a retransmissionrequest, or the like.

As such, by identifying each RLC PDU and storing into the buffer areausing the segment pointer SP, that is, the top address in which each RLCPDU is stored in the buffer area, it is possible to store the RLC PDUsinto RLC buffer 11 in order of transmission. Namely, even when thereception sequence is replaced, it is possible to store in order oftransmission.

Also, when a portion of the RLC PDUs is/are not received, RLC controller12 initiates a retransmission request of the above RLC PDU(s) to thetransmission side. When the RLC PDU of interest is received with delayafter the initiation of the retransmission request, an identical RLC PDUis received twice, based on the above retransmission request. In theabove case, the identity decision is made, for example, by comparinginformation identifying each RLC PDU such as the segment indicator SI.In case of being identical, it becomes necessary to discard one.However, such the above discard processing becomes unnecessary whenusing the segment pointer SP.

Namely, even when an identical RLC PDU is received twice, by overwritingin the address specified by the segment pointer SP, only one of theidentical RLC PDUs can be stored automatically. Thus, the identitydecision processing of the two RLC PDUs and the discard processingbecome unnecessary.

Also, when the retransmission request is made, there is a case oftransmission by being divided further at the time of the retransmission.In such a case, it becomes necessary to form the segment indicator SIwith a hierarchical structure (for example, assuming the segmentindicator of RLC PDU being retransmission requested to be SI=1, thesegment indicators of the two RLC PDUs further divided and retransmittedare set to be SI=1-1 and SI=1-2, or the like), and to add the segmentindicator SI area in the header.

In contrast, when using the segment pointer SP, even when the RLC PDU tobe retransmitted is further divided, the top address of the buffer areato store each divided RLC PDU may be specified as segment pointer SP.Thus, no additional header area is needed, and instead, only to storeeach RLC PDU into the address specified by the segment pointer SP isneeded. Moreover, even when the divided data length of each RLC PDU isunknown because of the redivision, it is not necessary to modify theconfiguration of RLC buffer 11.

The foregoing description of the embodiments is not intended to limitthe invention to the one details of the examples illustrated. Anysuitable modification and equivalents may be resorted to the scope ofthe invention. All features and advantages of the invention which fallwithin the scope of the invention are covered by the appended claims.

What is claimed is:
 1. A method of transmitting data from a radiotransmission apparatus to a radio reception apparatus, comprising:adding a sequential number, a first information indicating a position ofeach of divided data and a second information indicating whether each ofthe divided data is last data, to each of a plurality of divided datawhich is generated by dividing the data to be transmitted; andtransmitting the plurality of divided data including the sequentialnumber, the first information and the second information to thereception apparatus, the sequential number identifies the data to betransmitted.
 2. A radio transmission apparatus to transmitting data to aradio reception apparatus comprising: a processor configured to add asequential number, a first information indicating a position of each ofdivided data and a second information indicating whether each of thedivided data is last data to each of a plurality of divided data whichis generated by dividing the data to be transmitted; and a transmitterconfigured to transmit the plurality of divided data including thesequential number, the first information and the second information tothe reception apparatus, the sequential number identifies the data to betransmitted.
 3. A method of transmitting data from a radio transmissionapparatus to a radio reception apparatus, comprising: adding asequential number, a first information and a second information to eachof the plurality of divided data which is generated by dividing the datato be transmitted; and transmitting the plurality of divided dataincluding the sequential number, the first information and the secondinformation to the reception apparatus, the first information indicatesthe position of data, and the second information indicates whether it islast data.